ASTARTE. 471 



Subtriangularly suborbicular, equally broad as long, thick, 

 ponderous, opaque, moderately convex, covered with a tar-colour- 

 ed or yellowish chestnut glossy epidermis, which is ordinarily 

 adorned with darker and lighter concentric zones, beneath which 

 it is externally and internally whitish. The entire outer surface 

 is either smooth, or more rarely marked with obsoletely elevated 

 broad belts. Ventral margin much arcuated ; dorsal slopes 

 strong, the front moderately incurved, the hinder more or less 

 straight. Sides not greatly unequal ; the anterior the shorter, 

 and well rounded at its extremity ; the posterior obtusely round- 

 ed, its extreme tip convex. Beaks nearly central, greatly elevated, 

 a little inclined forwards ; lunule ovato-lanceolate, rather deeply 

 excavated, of a darker hue than the general colouring ; lozenge 

 not-much impressed, the ligament occupying two-fifths of it at 

 least. No umbonal ridge. Hinge margin very broad ; muscular 

 impressions profound, of moderate size ; lower margins internally 

 creuated. Diameter, an inch. 



The following description appears to apply to one of the fossil forms of 

 Astaiifi, .so common in our pleistocene strata : — 



Crasslna dej)ressa, Brown, 111. Conch. G. B. p. 96, pi. 3R, f. 2. 



" Shell compressed, transversely and obliquely subovate, iimbones ratlier pro- 

 minent and slightly reflexed, with a lanceolate deep lunule under them ; colour 

 of a dark reddish brown, with many flattened transverse ridges, <ind narrow shal- 

 low intervening furrows ; inside white, smooth ; margin plain, and slightly 

 thickened in the edge. Length, nine-eighths of an inch ; breadth, nearly- eleven- 

 eighths. This differs from C. Scotica in being more transvcmely elongated, oUique, 

 more compressed, with the basal line more parallel, tlte trafisverse ridges more nu- 

 merous, vei-y flattened, and almost obsolete. Found in tlte Frith of Forth, hut I 

 liave hitlwrto only met with dead and detaclied valves.^'' 



